Gingival Crevicular Fluid Matrix Metalloproteinase-8 Levels Predict Treatment Outcome Among Smokers With Chronic Periodontitis

Background: Molecular biomarkers are needed for diagnostic use in periodontal diseases. The aim of this study is to explore different gingival crevicular fluid (GCF) matrix metalloproteinase-8 (MMP-8) patterns in smokers and nonsmokers with chronic periodontitis (CP) and test the utility of baseline GCF MMP-8 levels in predicting categorically assessed treatment outcomes. Methods: The study population comprised 15 patients with CP (five non-smokers and 10 smokers). GCF sampling of five to seven periodontal sites per patient was done at baseline, post-treatment, and bimonthly during the maintenance period from 8 to 12 months. GCF MMP-8 levels were measured with an immunofluorometric assay. MMP-8 response patterns were explored by cluster analysis. The ability of baseline MMP-8 levels to predict categorical treatment outcomes was analyzed with receiver operating characteristic curves. Results: GCF MMP-8 response patterns could be clustered into two different site profiles among both smokers and non-smokers. Smoker site profiles 1 and 2 had significantly different clinical attachment level and gingival recession changes by the end of the maintenance period. In smoker sites, baseline MMP-8 levels significantly predicted the categorical treatment outcome. Conclusions: Baseline GCF MMP-8 levels strongly predict how MMP-8 levels behave during the maintenance period. In smoker sites, high baseline MMP-8 levels indicate weak treatment response.